There have been conventionally developed various deicing methods to prevent deterioration, of performances of a wind turbine due to adhesion of ice to the wind turbine.
US Patent Application Publication No. 2006/0018752 discloses a method of deicing a wind turbine blade by flowing the air heated by a heater in a channel provided through the wind turbine blade and a method of detecting ice adhering to the wind turbine blade. A thermographic system is used to detect the ice.
U.S. Pat. No. 6,890,152 discloses a method of detecting adhesion of ice to a wind turbine blade, vibrating at least a portion of the wind turbine blade, and shaking down the ice from the wind turbine blade. For example, a vibrator provided in the wind turbine blade generates acoustic wave to vibrate the wind turbine blade. The frequency of the acoustic wave is 5 to 500 Hz.
Japanese Unexamined Patent Publication No. 2004-84527 discloses an ice adhesion preventing operation control device for the wind turbine. The rotor of the wind turbine includes pitch-variable blades. The ice adhesion preventing operation control device for the wind turbine issues an instruction to reduce the pitch angle of each blade down to a predetermined pitch angle when a temperature is equal to or lower than a threshold value, a humidity is equal to or higher than a predetermined threshold value, a wind velocity is equal to or lower than a predetermined threshold value, and the wind turbine is stopped or in an idling or standby state. After issuing the pitch angle reducing instruction, the ice adhesion preventing operation control device for the wind turbine issues an instruction to actuate a main shaft brake connected to the rotor when the rotational velocity of the rotor is equal to or higher than a predetermined threshold value.